LPRDS ETS Lafayette Photovoltaic Research and Development System Energy Transfer Subsystem

Transcription

1 LPRDS ETS 2009 Lafayette Photovoltaic Research and Development System Energy Transfer Subsystem Final Presentation May 11, 2009 Lafayette College-ECE Dept.

2 Project Overview Project Overview Total investment of $40,000 in solar infrastructure to support student projects One semester team-based capstone senior design project 22 student team $4000 Budget (Not including Array cost and initial battery cost) Subject to a 55 page requirements document Technical Specifications National Electric Code (NEC) Article 690 on PV systems Reporting requirements (e.g. website, PDR reports, CDR reports, etc.) General Project Requirements (Maintainability, Sustainability, Reliability, etc.) Total of 104 requirements

3 Presentation Outline 1. Project Overview 2. ->System Input Solar Energy 3. System level design 4. Subsystem design 1. RPI 2. ESS 3. EDS 4. SCADA 5. Conclusion

4 Why solar energy? Energy Consumption Energy Consumption on the rise Causes: Population growth and technological developments Energy Sources Non-renewable resources such as Petroleum, Natural Gas, and Coal account for 85% of US energy consumption. Solar energy accounts for less than 0.5% of total consumption. Why? Economic Analysis A household system is not economical for Easton, PA A 20yr system has been calculated to cost $72, times cost of buying from the grid Technology will continue to improve Experts predict solar will play a role in the future energy market Cash Flow analysis (ES225)

5 System Input Solar Energy 10 GEPBp-200-MS modules connected in series configuration. 5 degree tilt because of wind loading. Average of 4 kwh/m 2 /day We calculated an expected power of our system 4.2kwh/day Insolation Curve IV Curve Provided by GE

6 Presentation Outline 1. Project Overview 2. System Input Solar Energy 3. ->System level design 4. Subsystem design 1. RPI 2. ESS 3. EDS 4. SCADA 5. Conclusion

7 Main Requirements Accept high voltage DC from the PhotoVoltaic Array. Output AC 120 volts, 60Hz +/- 0.05%. Total Harmonic Distortion <= 3% An Energy Storage System Autonomous Safety Interface SCADA (monitoring, control and display)

8 Summary of Project Accomplishments Number of requirements satisfied = 100 % requirements satisfied = 96.15% (note to senior management, that s an A) Major Requirements that were met 1) AC output at 120 volts RMS 2) Energy Storage System 3) Accepts DC high voltage from Photovoltaics 4) Autonomous Safety Interface Requirements Missed 1) AC output at 60Hz +/- 0.05% 2) THD <= 3% 3) Load Regulation <= 3% 4) Transient Response <= 5%

9 The illities Manufacturability 1) Mean Time To Repair less than 1 week 2) Spare parts in storage as order time is about 2 weeks. 3) System Tolerances Sustainability Economic sustainability considered for a household PV system Key components such as PVs and batteries considered for sustainability Ethical Considerations Kant s Categorical Imperative Maintainability 1) MIL-HDBK-472(Note 1) and MIL-STD-470B 2) gives a MTTR of 2.6 days Reliability 1) MIL-HDBK-217 delivers MTBF of 1071 hrs. (1000 hr. requirements)

10 Design Tools and Features Tools used: VTB Simulink (ECE433) PSpice (ECE323) AVR studio (ECE212) Linux (CS classes) PHP MySQL C++ (CS205) C (ECE212) PADS DxDesigner (ECE323) Quick Circuit Milling Machine Features: Commercial off the self (COTS) Sensors (current, temperature, voltage) Relays PIC Microcontroller PC Custom circuit design 7 PCB boards software

11 Safety Concerns Safety was an integral part of the design process Safety Lecture Safety plan (signed by all students) Commercial GFI Safety circuit High voltage/ low voltage isolation in all subsystems

12 System Design Supervisory Control and Data Acquisition Monitors the system for safety issues Energy Storage Sub-System 64 LiFePO4 Cells 205 Nominal Array Voltage 10 Ah leads to 2.35 kwh Controls the system states Raw Power Interface Ground fault protection Energy Delivery Sub-System Provides proper load to the batteries DC/AC conversion (Inverter)

13 State Transition Diagram

14 Presentation Outline 1. Project Overview 2. System Input Solar Energy 3. System level design 4. ->Subsystem design 1. ->RPI 2. ESS 3. EDS 4. SCADA 5. Conclusion

15 Raw Power Interface Main Requirements: Disconnect from PV Ground Fault Detection Provide Sensor Data for PV Array RPI Interior View RPI Exterior View Student-Designed PIC/Sensor PCB Layout

16 RPI Box Layout PCB with PIC *GFM Mounted on Box Door 30V+ & DC Indicators Safety Relay HV LV 15A Fuse Current Transformer Solid-State Relay System Power *Red Pattern Indicates Shielded HV Region Output Blocks

17 RPI Features Ground Fault Monitor- Bender RCMA420 Purchase for safety concerns Voltage, current and temperature sensors Voltage from PV array Voltage to EDS Current sourced from PV array Temperature inside enclosure PIC to perform data acquisition 10-bit A/D converter RS485 serial communication Separated into low and high voltage sides

18 RPI Sensor Designs HV Indicator Spice Simulation Custom Designed Sensors (Pictured): Voltage Sensors HV Indicator DC Power Indicator C.O.T.S.: Sensors: Current Sensors Temp. Sensors

19 RPI Summary RPI was a complete success Viable Final Version No revisions necessary Tested drawing power from the PV array Charged ESS batteries

20 Presentation Outline 1. Project Overview 2. System Input Solar Energy 3. System level design 4. ->Subsystem design 1. RPI 2. ->ESS 3. EDS 4. SCADA 5. Conclusion

21 Energy Storage System (ESS) Requirements 20 project requirement mapped to ESS Main requirements are listed below: Main Requirements R Specification Energy Accumulator is required to store excess energy Pass/ Fail Pass R Discharge power capacity of the ESS shall be able to meet the power requirements of the system Pass R Shutdown switch required. Pass R GPR Containers must have closable access ports for electrical probing of each extreme of the HV system. NiCd and Lead-Acid batteries may not be used. Pass Pass

22 ESS Design Parts Designed PCB Layout (fabricated off-site) PIC code HV (>30V) Indicator Voltage Sensors Isolated Relay Control PCB Metal Case Battery Technology Selection Battery Mounting Mechanism Parts Purchased DC-DC converters Relays Disconnect Switch Temperature and Current Sensors

23 64 3.2V LiFePO4 Cells in series 205V 10 Ah = 2KW of power Up to 70A discharge rate and 60A charge rate Clever and Safe Design When top is removed, there is no voltage greater than 14.8V in the battery compartment Makes maintenance easier individual packs can be swapped out Disconnect Switch Window and Indicator LEDs Batteries Steve s Knee Test Points

24 ESS-Schematics Features: PIC RS485 communication to SCADA Indicator Lights Voltage, Current, and Temperature Sensors Low Voltage sources of 5V and 12V Relay Control

25 Batteries charging/discharging- Test Results 3.65 V Charging 5A Rate Factory Curves 1.7hrs charge charge cycle cycle discharge 3.7 V 10A Rate OVERCHARGE 3.3 V cycle Discharging 0.8hrs 2.75V 5A Rate 1.7hrs 14.8V Trickle Charging 3.3 V 10A Rate 0.1hrs 2.57V 0.9hrs

26 ESS Photos Disconnect Switch Tightening Points Copper Plates 12.8V Pack Slot for 12.8V Pack Shield PCB Design (PADS) Disconnect Switch PIC Safety Relay System Power DC-DC RJ45 Safety System HV I/O Power Temperature Switch

27 ESS Summary ESS is a final part of the LPRDS-ETS Future Additions/Changes Voltage Ramping Circuit Battery Management System (BMS) Redesign Voltage Sensors

28 Presentation Outline 1. Project Overview 2. System Input Solar Energy 3. System level design 4. ->Subsystem design 1. RPI 2. ESS 3. ->EDS 4. SCADA 5. Conclusion

29 Energy Delivery System-DC to AC Converter 23 Total Requirements Major requirements listed below: Custom parts designed Requirement Specification Pass/Fail R R R R R R Provide 120 V RMS AC sinusoidal at 60Hz for the load with a max sustained current of 15Amps RMS 60Hz frequency is accurate to within 0.05%. Total Harmonic Distortion is less than 3% The system can be modified to work at 50Hz Load regulation is better than 3% for a 100% step load change Transient Response is less than 5% for a 100% step load change. Pass Fail Fail Pass TBD Pass One PCB board fabricated in- house with 2 revisions A copy-cat of the ESS board (fabricated off-site) for sensor values Budget spent- $1,020 Parts designed H-Bridge/Inverter Differential Voltage measurement Filter High Current Traces Parts purchased Isolation Transformer 12v DC-to-DC converter (hi-lo voltage isolation) microcontroller EDS Proto board2 layout

30 EDS Design Filter design and PWM scheme driven by THD and frequency requirements H-Bridge design based on high voltage (120Vac) and high current (15A) requirement Possible implementation of closed loop Inverter algorithm to meet voltage regulation requirement new power algorithm downloadable High and low side voltage signals required opto-isolators H-Bridge Filter Transformer Microcontroller

31 EDS Schematics - 1 Fuse IGBT Features: 4 IGBTS 2 gate drivers 2 opto-isolators High voltage input goes through a 16A fuse Opto- Isolators Gate Drivers

32 EDS- PWM Scheme PSpice Simulation Unipolar Sine PWM IGBT Drive Signals Measured Result from Low Voltage Prototype

33 EDS-Filter LC Filter 3dB at 684.2Hz (simulated) LC Filter EDS Board Simulated AC Response of Filter

34 Measured data from the inverter 210v DC input / 124 RMS AC at 60.5Hz 50 ohm load 210v DC input / 124 RMS AC at 60.5Hz 25 ohm load 1 st Harmonic (60 Hz) 3 rd Harmonic (180 Hz) 5 th Harmonic

35 Interface of EDS to ESS (Batteries) Blew up! High Voltage to Low Voltage isolation worked! High Voltage parts destroyed Low Voltage survived Safety Plan (important) Possible cause: Current Surge Future Work: Use a Start up Circuit Additional Simulations

36 Presentation Outline 1. Project Overview 2. System Input Solar Energy 3. System level design 4. ->Subsystem design 1. RPI 2. ESS 3. EDS 4. ->SCADA 5. Conclusion

37 SCADA - Overview Supervisory Control and Data Acquisition Monitor and log critical values in the system Provide manual control of the system Provide a useful interface for displaying the collected data Major components Hardware (Custom PCB) Software PIC C language PC C++, MYSQL, Linux OS, PHP, C Communications protocol RS232 and RS485

38 SCADA - Software Top Level Diagram Top Level SCADA SoftwareArchitecture The different color boxes denote different processes API To SCADA PIC (232) SSC001 Comm Interface SSC003 Input Manager V6 SSC002 Monitor SSC008 Database Interface (PHP) SVN ver. Control (CS205) Design principles (CS205) SSC010 SSC004 Database SSC005 Database Interface C++ SSC006 System State Manager SSC009 System State Manager Inferface (PHP) Website (Graphing) To Network (Ethernet) SSC007 Demo Application To SCADA PIC (232) Intraprocess calls Files PHP-MYSQL interaction MYSQL++

39 Update System State SCADA - Software Operation Overview Poll SSC001 Comm Interface SSC002 Monitor Check Values Request the latest Request Give me the the latest list values of inputs from the to list latest of inputs Input to poll PICs check values SSC003 Input Manager Store in database SSC004 Database SSC005 Database Interface C++ SSC006 System State Manager

40 SCADA - Software Operation Overview Poll SSC001 Comm Interface SSC002 Monitor Check Values SSC003 Input Manager Store in database SSC004 Database SSC005 Database Interface C++ SSC006 System State Manager Update System State -If values not within acceptable boundaries, a fault has occurred. -System State manager is informed.

41 SCADA - Software Operation Overview Poll SSC001 Comm Interface SSC002 Monitor Check Values SSC003 Input Manager Store in database SSC004 Database SSC005 Database Interface C++ SSC006 System State Manager Update System State

42 SCADA - Software Operation Overview Poll SSC001 Comm Interface SSC002 Monitor Check Values SSC003 Input Manager Store in database SSC004 Database SSC005 Database Interface C++ SSC006 System State Manager Update System State New state depends on: User requests Voltages at load and batteries Faults reported

43 SCADA Communication RPI PCB EDS PCB ESS PCB RS 485 World Wide web PC Ethernet RS 232 SCADA PCB Display Board Ribbon Cable Connection

44 SCADA Sensor Communication 3 Types of Sensors (Voltage, Current, and Temperature) RPI Sensors EDS Sensors ESS Sensors PIC PIC PIC RS 485 PC RS 232 SCADA PCB Voltage Sensors Temp. Sensors Current Buffered Sensorsresistive dividers Bidirectional Calibrated Linear Hall using effect voltage test type data sensor output Calibrated scaling factor and offset Sensor Value = A/D value *.005v/bit * Scale factor

45 SCADA Board Schematic Relay PIC Ribbon Cable Connector To Display Board

46 SCADA Board Serial Communication Schematic TTL RS 485 RS 232

47 SCADA Board Designed using PADs Software Fabricated Board

48 SCADA Features Website URL: lprds.aec.lafayette.edu Data history Plots Maintenance picolcd Screen Display board

49 Presentation Outline 1. Project Overview 2. System Input Solar Energy 3. System level design 4. Subsystem design 1. RPI 2. ESS 3. EDS 4. SCADA 5. ->Conclusion

50 Engineering Management Results -Budget Current Budget Cost $3400 Andy Misc. Costs - $400 SAFETY TOTAL $ % TOTAL SCADA $ % ICD TOTAL $ % TOTAL ESS $ % RPI TOTAL $ % EDS TOTAL $1, % RPI TOTAL EDS TOTAL TOTAL ESS TOTAL SCADA SAFETY TOTAL ICD TOTAL $200 under BUDGET! enough to order food rather than cook our own. ECE Dept absorbed $4400

51 Conclusion-Results Total of 5735 project hours or $172,059 (at $30/hr) Developed 7 UNIQUE BOARDS! (RPI, SCADA, SCADA-555, ESS, EDS- ADAPTED-ESS, EDS-PROTO1, EDS-PROTO2). Almost one for every 3 students RPI tested and working correctly ESS tested and working correctly Mechanical layout complete Battery management system needed EDS with partial functionality Proto-type completed with basic functionality SCADA with partial functionality

52 Conclusion What is next? Buck Converter- increase power intake 12-15% Battery Current Control Algorithm increase efficiency in storing energy in the batteries (LiFePo 4 has a complicated charging curve) Grid Tie allow us to share electricity with the grid Motor control and electric vehicles

53 Thanks To Dr. Jemison Mr. Nadovich Andy Langoussis Nicolette Stavrovsky Doug Wood Chris Lett

54 Questions?